Butterflies in
Shetland
An
isolated island group such as Shetland inevitably has a restricted fauna
and flora. The Lepidoptera list currently stands at under 300 species, a
disappointing garden list for southern England. Nevertheless, this list
includes 14 species of butterfly, although many are just vagrants and
records have not been systematically collected until recently, beginning
in 1978 on Fair Isle and 1990 in the rest of Shetland. The following
summarises the occurrences of butterflies in Shetland.
Large White Pieris brassicae
The
only resident butterfly in Shetland, although it's origins as a breeding
species are a little obscure. It was obviously rare at the beginning of
the century as although it is mentioned in some early lists, Bryan Beirne
writing in 1945 could find no certain records. Local legend records that
the species arrived in Shetland during the last war, imported in NAAFI
cabbage an was exchange made in the early part of the 20th
century involving Shetland Hedgehogs being swapped for Large White
caterpillars from Orkney. However, Large Whites certainly occur as natural
migrants, for example on Fair Isle, where there are no recent breeding
records although there are records on average every second year. Whatever
their origins, whether natural colonisation, deliberate or accidental
introduction by man or a combination of the three, the species may be a
common pest on the islands of Mainland, Unst, Yell and Whalsay, although
it remains a scarce migrant on the other islands. The local resident
population fluctuates, and in the early years of the 21st century it has
become relatively scarce, especially on Unst. Local adults can be seen
between June and early August but are migrants may be seen in May and
later in the autumn until early October. Migrants are fairly scarce - just about annual
in spring but rarer in autumn.
Common Blue Polyommatus icarus
Resident in Shetland until quite recently. Although not recorded by an
entomologist until it was seen by Barry Goater at Quendale in 1968,
speaking to older residents of Dunrossness, the southernmost part of
Mainland, suggests that the species was actually quite regularly seen in
the 1950s and 60s. In addition, the Monks Wood Biological Records Centre
have about ten records on their computer database, all from 1970-1975 and
all from Dunrossness. Since 1980 there have only been two certain records,
in Dunrossness in 1991 and on Fair Isle in 1990, although intriguingly the
Dunrossness record was at a previous breeding site. However, it would
appear we have lost this butterfly as a breeding species.
Red Admiral Vanessa atalanta
Recorded annually in Shetland. Since 1990 when recording began throughout
the islands there have never been fewer than 30 records in a year, while
in several years there have been several hundred. The earliest record was on Foula on
20th April 1996, but most records are in June to August, especially July.
The most notable recent influxes occurred in June 1990, May/June 1992,
early October 1992, July 1994, late August 1997 and late June 1999. Autumn
records are usually scarce, although there were several in September 1995
and 1999 and there was a sudden arrival of over 50 between 1st-5th October
1992. October records include an unknown number of locally bred adults and
there are records right through to the last day of the month, although
there are no November records. Although it was formerly thought to be very
rare, it is now apparent that Red Admiral breeds in Shetland in most
years. The foodplant is Nettle Urtica dioca. There is no evidence
to suggest Red Admirals can ever overwinter in Shetland. Indeed throughout
Britain this species only usually occurs as a long-distance migrant from
southern Europe.
Painted Lady Cynthia cardui
Occurs
in most years, often in association with arrivals of Red Admirals. Usually
this is the scarcer of the two species, although interestingly it is the
most regularly recorded species from Fair Isle with almost annual records
there since recording began. Fair Isle records include notable influxes in
September 1978, June 1980 and particularly the famous invasion into
Britain of August 1980, when there were over 300 on the island on the 1st.
Such influxes must have affected the rest of Shetland, but any records
have been lost. Breeding records are much scarcer for this species than
the last, although there are a few on record, especially in 1994 and 1996
when good numbers occurred throughout the islands. The foodplants are
thistles Cirsium or Carduus. The earliest sighting of an
adults so far are individuals on Foula and Fair Isle on 3rd May 1997 with
a few autumn records as late as early October. Although this species can
breed in Britain it cannot overwinter and most British specimens are
believed to originate in North Africa.
Small Tortoiseshell Aglais urticae
Occurs just about every year although it is scarce. Up to 35 were on Fair
Isle in August 1980, but the 10 recorded throughout Shetland in 1992 were
almost as exceptional. There are no documented breeding records
so far although the foodplant is Nettle Urtica dioca. All the
sightings have so far fallen between mid May and mid October with no
obvious pattern or favoured month apparent. Unlike the Painted Lady, this
butterfly overwinters in Britain. Shetland specimens probably originate
from either Britain or Scandinavia, with the preponderance of Shetland
records from Fair Isle suggesting Britain is more likely.
Peacock
Inachis io
Recorded on over 50 occasions. The first two
records were in the 1960s, followed by at least eight in 1975. Then there
were just three further records until influxes of about 13 in 1994, mainly
in the second half of August and another influx of at least 15 in 1995,
again mainly in August. Since then there small influxes in 1997 and 1998,
but just one in 1996 and a blank in 1998. There were about 12 in 1999 and
four in 2002. Although August is the most
favoured month, records of butterflies found dead in buildings in November
and December, and flying in sunshine in January indicate that hibernation
is at least attempted in the islands. There are no recorded breeding
records. Like the Small Tortoiseshell, Shetland specimens probably
originate in either Britain or Scandinavia.
Small White Pieris rapae
This
species could be easily missed amongst the commoner Large Whites but it
has occurred on several occasions. The three most recent records have all
been from Fair Isle in June 1978, August 1989 and July 1992 and one found
indoors in Nesting in November 2000. Others have
supposedly occurred on Mainland and there is a record from Yell in the
1970s but no other details have been traced.
Camberwell Beauty Nymphalis antiopa
This
is one of the most spectacular butterflies to be found in Britain where it
is a scarce migrant despite being found over most of the continent. It has
been recorded in Shetland on at least ten occasions, on Foula in August
1896, Scalloway on an unknown date in the 19th century, Burrafirth in August
1901, Bressay in July 1976, Lerwick in August 1982, Fetlar in 1982, Foula
in August 1995, Bressay in September 1995, Exnaboe in August 1996,
Scousburgh in July 1999 and Hermaness in August 2002.
Clouded Yellow Colias croceus
A
noted migrant the Clouded Yellow has been recorded in Shetland four times,
the first three records coming from Fair Isle in July/August 1980 and May
and August 1992 with another on Bressay in June 1998. Two other reports of
this species in July 1992 were unfortunately too uncertain to be
acceptable.
Swallowtail
Papilio machaon
The
Swallowtail has surprisingly occurred twice in Shetland in recent years.
One was found dead beside the road at Voe on Mainland on 2nd August 1994
and a second individual was seen on Fair Isle on 9th September 1995 - the
two records comprising the only certain wild records for Scotland.
Several species have only occured once in Shetland. These are - a
Meadow Brown Maniola jurtina seen twice on Fair Isle in June
1980 (presumably the same individual); a Small Heath Coenonympha
pamphilus also seen on Fair Isle on 14th June 1980; a Monarch
Danaus plexippus, a native of North America, at Bixter, West
Mainland on 14th September 1941 (another on Fair Isle on 1st September
2002 was seen too briefly to be certain); and a Green-veined White Pieris
napi on Bressay on 6th July 1994.
Finally there is a group of butterflies which have reputedly been seen in
Shetland, but for which there is no real evidence. The most notorious of
these is the Large Heath Coenonympha tullia, which was quoted as
Shetland's only indigenous butterfly by almost every relevant book up
until a few years ago. This appears to have arisen on the basis of a
statement by Birchall in a book by Humphreys and Westwood published in
1841. Once it had been repeated by such authorities as South, whose book
on butterflies was the standard text for over 60 years, the error became
hard to eradicate, but there is no evidence of this species ever having
occurred in Shetland.
Two
specimens of Dingy Skipper Erynnis tages in the British Museum
labelled Shetland 1888 are presumed to be wrongly labelled, while the
sighting of Northern Brown Argus Aricia artaxerxes by the botanist
Druce cannot be substantiated (indeed it was most likely to be a female
Common Blue, not known to occur in the islands at the time). A probable Small Copper Lycaena phlaeas
was seen in September 1997.
Nature in Shetland
